Polyethylene terephthalate coated with transferable minute specks of magnetic ink



July 30, 1963 T. MAIERSON ETAL 3,099,571

HTHALATE COATED WITH TRANSFERABLE MINUTE POLYETHYLENE TEREP SPECKS OF MAGNETIC INK Filed May 5, 1958 FIG. I

FIG.- 2

um 0L m SH. R E S H N REC R m w m N V T EEK A Wmm m DHM m OD T. mmm TFH United dtates Patent Office 3,099,571 Patented July 30, 1963 3,099,571 POLYETHYLENE TEREPHTHALATE CDATED WITH TRANSFELE MINUTE SPECKS F MAGNETIC INK Theodore Maierson, Frederick C. Schiller, and Harry N. Vosmer, Dayton, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed May 5, 1958, Ser. No. 733,141 4 Claims. (Cl. 117-36.1)

This invention relates to a tape for transferring ink including particulate magnetic material to a receiving medium by means of a blow from an impression means or a character-bearing means.

It has been known to provide sheets of transfer material having magnetic transfer coatings thereon, such as shown in the United States Patent No. 2,744,031, which issued on the application of Robert E. Mumma on May 1, 1956, wherein a continuous wax coating containing magnetic oxide material was applied to a thin base sheet through which a blow impression was made to transfer the magnetic material to an underlying receiving web such as paper so as to form characters or marks of the magnetic material thereon, which characters or marks may be sensed by suitable magnetic pick-up means.

In applications of such transfer material to high-speed printing such as is used in connection with electronic accounting systems, wherein data is to be recorded as magnetic characters, which characters may be sensed by magnetic pick-up heads, it becomes important that the material be transferred completely with accurate outlines which are dimensionally correct, which accuracy is rendered possible by the tape of this invention.

This invention provides a tape in which the magnetic material, in a binder, is applied in a stippled manner to a thin backing web made of a strong tilm material such as Mylar, which is polyethylene terephthalate, of the thickness of approximately 710,000 of an inch, the novel feature being of the application of such magnetic material to the backing web as a coating having a profusion of closely-spaced specks of the ink, caused by the stippling, which specks are practically invisible to the unaided eye because of their small dimensions and close proximity.

The magnetic coating in the binder will be called magmetic ink for the purposes of this disclosure, and it is applied to the backing web by a rotogravure roller which is inked in the manner of the rotogravure rolls. Preferably, the depressions which hold the ink in the rolls are of inverted truncated pyramidal contours to 'form a series of cups separated by lands. The number of cups per square inch may be as high as 40,000, and the cups are etched or knurled into a cylindrical sheet or printing roll with the corners of the cups being alined respectively in one direction with the axis of the roll and in the other direction at right angles thereto.

FIG. 1 shows a cross section through a portion of the printing roll on a much-enlarged scale, 20 representing one of the truncated pyramidal cups with the separating lands 21.

FIG. 2 shows a rotogravure roll 22 having an etched or knurled printing surface.

FIG. 3 is a section through an enlarged portion of a tape made according to this invention, showing the backing web 23 and the ink specks 24.

A typical ink contains minute particles of black magnetic iron oxide in a binder, the particles having an average diameter of less than one micron. The binder material preferably is a mixture in proportions as follows, by weight: castor oil, 14 parts; black magnetic iron oxide,

2 42 parts; paraifin wax, 10 parts; polyethylene wax, 44.7 parts. The ink is heated to 260 degrees Fahrenheit and applied to the rotogravure roll, which is wiped with a doctor blade, leaving ink in the cups. The printing impression is made onthe web from the ink in the cups as a continuous system of practically invisible and closely-spaced stipple specks, and then the printed film is transported to where it may cool, so that the applied ink will harden to .form a solid. The proportions of iron oxide and binder materials may be varied considerably.

The magnetic tape made according to the above process, when used in conjunction with conventional raised type or hammer printing methods, will transfer to the receiving sheet practically all of the coating on that portion of the web which receives the blow impression of the raised type or hammer surface. The low portions be tween the specks of ink form easy fracture places to prevent irregular characters from being printed. The transferred stipple specks tend to merge into a continuous printed character representing the type.

The substantial isolation of the microscopic stipple specks of ink on the tape, and the clean break between them on printing, give the printed characters very fine definition, which is not possible with such magnetic tape which has a continuous smooth coating.

The impression need not be through the web, but may be through a copy sheet or a receiving sheet placed against the coated surface, the hammer blow through the copy sheet lifting a corresponding portion of the coating onto the side of the receiving sheet next to the coating.

What is claimed is:

1. A transfer backing film of polyethylene terephthalate having a profusion of microscopic substantially isolated, closely spaced stipple specks derived from truncated pyramidal contour deposits of transferrable magnetizable ink which may be transferred to a receiving sheet by a transfer printing operation, the stipple specks of ink transferred to the receiving sheet merging by force of the transfer printing operation to produce a clearly defined character of magnetizable material.

2. A transfer sheet consisting of a supporting film of polyethylene terephthalate having a transfer coating of magnetizable material, said coating consisting of a profusion of closely spaced stipple specks of magnetizable material forming a discontinuous system so that in transferring the magnetic material to a receiving sheet only shearing between the stipple specks of the coating is required.

3. A supporting film of polyethylene terephthalate of approximately five ten-thousandths of an inch in thickness having a transfer coating consisting of approximately 40,000 substantially isolated stipple specks of magnetic iron oxide ink per square inch.

4. A transfer member consisting of a film of polyethylene terephthalate having a transfer coating consisting of closely spaced minute stipple specks of magnetic ink.

References Cited in the file of this patent UNITED STATES PATENTS 1,91 1,59'2 Supligeau et a1 May 30, 1933 2,408,147 Kneale Sept. 24, 1946 2,649,386 Snowman Aug. 18, 1953 2,744,031 Mumma May 1, 1956 2,810,661 Newman et a1 Oct. 22, 1957 OTHER REFERENCES Ilford: Manual of Process Work by Clerc, 4th ed., 1946 (pp. 287-290, 292, 293, 295-297, relied on). 

1. A TRANSFER BACKING FILM OF POLYETHYLENE TEREPTHALATE HAVING A PROFUSION OF MICROSCOPIC SUBSTANTIALLY ISOLATED, CLOSELY SPACED STIPPLE SPEAKS DERIVED FROM TRUNCATED PYRAMIDAL CONTOUR DEPIOSITS OF TRANSFERRABLE MAGNETIZABLE INK WHICH MAY BE TRANSFERRED TO A RECEIVING SHEET BY A TRANSFER PRINTING OPERATION, THE STIPPLE SPEAKS OF INK TRANSFERRED TO THE RECEIVING SHEET MERGING BY FORCE OF THE TRANSFER PRINTING OPERATION TO PRODUCE A CLEARLY DEFINED CHARACTER OF MAGNETIZABLE MATERIAL. 